Epidemiological studies of periodontal diseases.
D000293:Adolescent; D000328:Adult; D002648:Child; D005006:Ethnicity; D005260:Female; D006306:Health Surveys; D006801:Humans; D007194:India; D007492:Iran; D008297:Male; D009549:Nigeria; D009747:Nutritional Physiological Phenomena; D009909:Oral Health; D010510:Periodontal Diseases / Q000453:epidemiology* / Q000209:etiology; D010512:Periodontal Index; D012959:Socioeconomic Factors; D013188:Sri Lanka; D013397:Sudan; D014944:World Health Organization